Highly pathogenic Avian Influenza virus A/H5N1 infection in vaccinated meat duck flocks in the Mekong delta of Vietnam

Journal article

We investigated episodes of suspected highly pathogenic avian influenza (HPAI)-like illness among 12 meat duck flocks in two districts in Tien Giang province (Mekong Delta, Vietnam) in November 2013. In total, duck samples from 8 of 12 farms tested positive for HPAI virus subtype A/haemagglutinin 5 and neuraminidase 1 (H5N1) by real-time RT-PCR. Sequencing results confirmed clade of 2.3.2.1.c as the cause of the outbreaks. Most (7/8) laboratory-confirmed positive flocks had been vaccinated with inactivated HPAI H5N1 clade 2.3.4 vaccines <6 days prior to onset of clinical signs. A review of vaccination data in relation to estimated production in the area suggested that vaccination efforts were biased towards larger flocks and that vaccination coverage was low [21.2% ducks vaccinated with two shots (range by district 7.4-34.9%)]. The low-coverage data, the experimental evidence of lack of cross-protection conferred by the currently used vaccines based on clade 2.3.4 together with the short lifespan of meat duck flocks (60-70 days), suggest that vaccination is not likely to be effective as a tool for control of H5N1 infection in meat duck flocks in the area.

Authors: Cuong, N; Truc, V; Nhung, N; Thanh, T; Chieu, T

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Wiley
• Journal: Transboundary and Emerging Diseases
• Publication date: 2016-01-08
• DOI: 10.1111/tbed.12470
• EISSN: 1865-1682
• ISSN: 1865-1674
• Language: English
• Keywords: zoonoses; one health; avian influenza virus; H5N1; vaccine; veterinary epidemiology; duck